The Sanders team's explanation of the incident has gradually changed since it was first confirmed late Thursday, initially saying that only a single “low-level” staffer accessed the Clinton data and that none of it was saved.

But the database logs created by NGP VAN show that four accounts associated with the Sanders team took advantage of the Wednesday morning breach. Staffers conducted searches that would be especially advantageous to the campaign, including lists of its likeliest supporters in 10 early voting states, including Iowa and New Hampshire. Campaigns rent access to a master file of DNC voter information the party, and update the files with their own data culled from field work and other investments.

After one Sanders account gained access to the Clinton data, the audits show, that user began sharing permissions with other Sanders users. The staffers who secured access to the Clinton data included national data director Josh Uretsky, who was fired on Thursday, and his deputy, Russell Drapkin. The two other usernames that viewed Clinton information were “talani" and "csmith_bernie," created by Uretsky's account after the breach began.

Though the Sanders campaign initially claimed that it had not saved Clinton data, the logs show that the Vermont senator’s team created at least 24 lists during the 40-minute breach, which started at 10:40 a.m., and saved those lists to their personal folders. The Sanders searches included New Hampshire lists related to likely voters, "HFA Turnout 60-100" and "HFA Support 50-100," that were conducted and saved by Uretsky. Drapkin's account searched for and saved lists including less likely Clinton voters, "HFA Support <30" in Iowa, and "HFA Turnout 30-70"' in New Hampshire.

Uretsky told CNN on Friday that he probed the Clinton data to get a sense of the full extent of the problem, but the breach was reported to NGP VAN by a third party, not by the Sanders campaign, a source familiar with the investigation said. "We knew there was a security breach in the data, and we were just trying to understand it and what was happening," he said. "To the best of my knowledge, nobody took anything that would have given the (Sanders) campaign any benefit."